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United States Patent |
5,232,620
|
Hensler
,   et al.
|
August 3, 1993
|
Sodium tripolyphosphate composition and method of producing it
Abstract
A granular STPP suitable for detergent compositions which is non-caking in
non-agitated water is produced by wetting anhydrous phase II STPP granules
and drying the granules to remove free water. The resulting granules, when
incorporated in detergent compositions, form a free flowing detergent
slurry in detergent dispensing systems.
Inventors:
|
Hensler; Paul L. (Lawrence, KS);
Arnold; Ronald E. (Lawrence, KS);
Himpler; Hilary A. (Charlotte, NC)
|
Assignee:
|
FMC Corporation (Philadelphia, PA)
|
Appl. No.:
|
662055 |
Filed:
|
February 28, 1991 |
Current U.S. Class: |
510/108; 423/315; 510/231; 510/233; 510/506; 510/510; 510/512; 510/534 |
Intern'l Class: |
C11D 003/06; C11D 009/14; C11D 011/00 |
Field of Search: |
423/315,208,179
252/135,174.21,174.14,156
|
References Cited
U.S. Patent Documents
3030180 | Apr., 1962 | Bigot | 423/315.
|
3356447 | Dec., 1967 | Tafler | 423/315.
|
3361675 | Jan., 1968 | Fuchs | 423/315.
|
3383321 | May., 1968 | Davis et al. | 252/135.
|
3446580 | May., 1969 | Fuchs | 23/106.
|
3469938 | Sep., 1969 | McLeod et al. | 23/107.
|
3637339 | Jan., 1972 | Gray | 252/99.
|
3672826 | Jun., 1972 | Hornig et al. | 23/106.
|
3751222 | Aug., 1973 | Gobert | 8/111.
|
3770644 | Nov., 1973 | Huttinger et al. | 252/135.
|
3852212 | Dec., 1974 | Groening et al. | 252/135.
|
3993734 | Nov., 1976 | Verdier et al. | 423/315.
|
4251498 | Feb., 1981 | Hensler et al. | 423/315.
|
4255274 | Mar., 1981 | Hensler et al. | 252/135.
|
4276326 | Jun., 1981 | Joshi | 427/220.
|
4315898 | Feb., 1982 | Lutz | 423/315.
|
4362641 | Dec., 1982 | Peterson | 252/135.
|
4427417 | Jan., 1984 | Porasik | 252/135.
|
4656019 | Apr., 1987 | Hensler | 423/315.
|
4671948 | Jun., 1987 | Couffin et al. | 423/315.
|
4770865 | Sep., 1988 | Highfill | 423/315.
|
4853144 | Aug., 1989 | Highfill | 252/135.
|
4857287 | Aug., 1989 | Dick et al. | 423/315.
|
Other References
Phosphorus and It's Compounds, vol. I, John R. Van Wazer, 1958, pp. 645,
648-650.
|
Primary Examiner: Lieberman; Paul
Assistant Examiner: Higgins; Erin M.
Attorney, Agent or Firm: Ianno; Frank, Andersen; Robert L.
Claims
We claim:
1. In the process of preparing detergent formulations containing sodium
tripolyphosphate, the improvement that consists essentially of employing
as said sodium tripolyphosphate ingredient moisturized granules of
essentially phase II sodium tripolyphosphate, containing no more than
about 5% by weight of phase II sodium tripolyphosphate, which yields a
non-caking, free flowing detergent formulation when added to water in the
absence of agitation, and wherein said added sodium tripolyphosphate is
produced by:
a) forming granules of anhydrous, essentially phase II sodium
tripolyphosphate by heating of sodium orthophosphate salts,
b) contacting the sodium tripolyphosphate granules with a quantity of
water, the upper limit being below the point at which the wetted granules
commence to coalesce and are no longer free flowing, the lower limit of
water being that quantity which is sufficient to maintain the free flowing
granular character of the STPP granules in aqueous media,
c) drying the wetted sodium tripolyphosphate granules from b) at a
sufficient temperature to expel unbound water but not the bound water, so
that no more than 0.5% by weight of unbound water is present, and
d) recovering the moisturized and dried, essentially phase II granules from
c) containing no more than about 5% by weight of phase I sodium
tripolyphosphate.
2. The process of claim 1 wherein the amount of bound water in the
recovered, moisturized, essentially phase II sodium tripolyphosphate is
from about 5% to about 7% by weight.
3. The process of claim 1 wherein the STPP granules in step a) are about
100% -14 mesh, and about 15% -100 mesh and in step d) about 100% -14 mesh,
and about 3% -100 mesh.
4. The process of claim 1 wherein the granules are dried from about
60.degree. to 80.degree. C.
5. The process of claim 5 wherein the drying is carried out in a rotating
tube dryer.
6. The process of claim 1 wherein the essentially phase II STPP granules
contain no more than 5% by weight of phase I STPP.
7. In the process of preparing detergent formulations containing:
a) sodium tripolyphosphate in amounts of about 10% to about 50% by weight,
b) alkalinity-imparting ingredients in amounts of about 10% to about 60% by
weight,
c) surface-active ingredients in amounts of about 0% to about 20% by
weight,
d) oxidizing, soil and stain removing ingredients in amounts of about 0% to
about 12% by weight,
the improvement that consists essentially of employing as the ingredient in
a) above, a sodium tripolyphosphate (STPP) comprising moisturized granules
of essentially phase II STPP containing no more than about 5% by weight of
phase I sodium tripolyphosphate which yields a non-caking, free flowing
detergent formulation when added to water in the absence of agitation,
said STPP produced by:
e) forming granules of anhydrous, essentially phase II STPP by heating of
sodium orthophosphate salts,
f) contacting the STPP granules with a quantity of water, the upper limit
being below the point at which the wetted granules commence to coalesce
and are no longer free flowing, the lower limit of water being that
quantity which is sufficient to maintain the free flowing granular
character of the STPP granules in aqueous media,
g) drying the wetted STPP granules from f) at a sufficient temperature to
expel unbound water but not the bound water, so that no more than 0.5% of
unbound water is present, and
h) recovering the moisturized and dried, essentially phase II granules from
g) containing no more than about 5% by weight of phase I sodium
tripolyphosphate.
8. Process of claim 7 wherein the component b) is selected from the group
consisting of sodium carbonate, sodium hydroxide and sodium silicate and
mixtures thereof.
9. Process of claim 7 wherein the component c) is a nonionic surface-active
agent.
10. In the process of preparing detergent formulations containing:
a) sodium tripolyphosphate in amounts of about 10% to about 50% by weight,
b) alkalinity-imparting ingredients in amounts of about 10% to about 60% by
weight,
c) surface-active ingredients in amounts of about 0% to about 20% by
weight,
d) oxidizing, soil and stain removing ingredients in amounts of about 0% to
about 12% by weight,
the improvement that consists essentially of employing as the ingredient in
a) above, a sodium tripolyphosphate (STPP) comprising moisturized granules
of essentially phase II STPP containing no more than about 5% by weight of
phase I sodium tripolyphosphate which yields a non-caking, free flowing
detergent formulation when added to water in the absence of agitation,
said STPP produced by:
e) forming granules of anhydrous, essentially phase II STPP by heating of
sodium orthophosphate salts,
f) contacting the STPP granules with water so that the STPP granules
contain bound water in amounts of from about 3% to about 10% by weight,
g) drying the wetted STPP granules from f) at a temperature of about
60.degree. C. to about 80.degree. C. to expel unbound water but not the
bound water, so that no more than 0.5% of unbound water is present, and
h) recovering the moisturized and dried, essentially phase II granules from
g) containing no more than about 5% by weight of phase I sodium
tripolyphosphate.
Description
This invention relates to sodium tripolyphosphate. More particularly, the
invention pertains to a form of sodium tripolyphosphate employed in
detergent compositions exhibiting improved resistance to caking when added
to water.
Sodium tripolyphosphate (STPP) is an important industrial chemical which
has a variety of uses and applications. It is, for instance, a key
component in the manufacture of detergents and in food processing.
STPP is conventionally obtained by the calcination of sodium orthophosphate
salts. A typical commercial procedure involves reacting phosphoric acid
and an alkali sodium compound, such as soda ash, to first produce an
aqueous sodium orthophosphate mixture having an Na:P molar ratio of 5:3
commonly referred to as "ortho liquor". This is then dried and the
resulting solid orthophosphate mixture heated (calcined) at sufficient
temperatures to form anhydrous STPP.
The drying and heating of the ortho liquor can be carried out sequentially
in a rotary dryer or in a one-step operation by means of spray drying.
STPP prepared in a rotary dryer consists of bulky masses which are crushed
and screened to yield a granular material. Spray drying provides granular
STPP directly.
STPP derived from the calcination of orthophosphates is of two types
designated as phase I and phase II, depending on the calcination
temperature, phase I predominantly at higher temperatures, phase II at
lower temperatures. Generally speaking, the ratio of the phases can be
controlled by calcining at temperatures ranging from about 450.degree. C.
for maximum phase II yields and at 600.degree. C. for maximum phase I
yields. A representative commercial STPP, having a phase I/phase II ratio
of 25 to 75, can be manufactured in a rotary dryer at calcination
temperatures of about 515.degree. C. to 530.degree. C.
As is well known in the detergent art, a characteristic property of
anhydrous STPP is its tendency to undergo caking when added to water in
the absence of stirring or agitation. Caking is particularly pronounced
with single phase material which yields a hard cake. Commercial 25/75
blend may or may not form a hard cake, being somewhat unpredictable in
this respect, but any caking tendency which reduces its surface area and
hence, its dissolving ease is unacceptable.
The caking behavior of STPP has proved troublesome in connection with some
of the newly developed detergent systems which meter heavy duty detergent
into large industrial and institutional dishwashers and automatic
laundering devices. These systems are designed to protect workers and
personnel from coming in contact with highly alkaline cleaning
compositions.
In operating these systems, a charge of detergent is automatically
delivered to the washing zone of the washing machine from a reservoir in
the detergent dispenser. It is at this point that the STPP caking problem
arises. On contact with water, a STPP containing detergent placed in the
detergent dispenser is likely to be transformed into a monolithic lump or
a viscous, sticky mass, depending on the phase type or phase ratio. In any
event, the diminished surface area of the coalesced detergent reduces its
rate of dissolution with consequent reduction in cleaning action.
It is known that the caking tendency of conventional STPP, having both
phase I and phase II in substantial amounts, can be ameliorated by
subjecting it to a moisturizing treatment. In this procedure, granules of
25/75 phase I/phase II STPP are contacted with water in such a manner that
1% to 2% water is evenly distributed on the granules. A typical
moisturizing technique consists in spraying the STPP granules with water
while maintaining them in a state of agitation.
Although the treatment aforesaid results in a non-caking STPP, it is still
unsuited for the newly developed industrial detergent delivery systems.
When charged into the detergent dispenser of an automatic dishwashing or
laundering machines, the treated STPP forms a sticky globular mass which
functions little or no better than the hard caking or untreated STPP.
A form of granular STPP which is non-caking and free flowing when added to
water without agitation has now been discovered for use in preparing
detergent formulations, wherein said STPP is moisturized granules of
essentially phase II STPP which yields a non-caking, free flowing
detergent formulation when the formulation is added to water in the
absence of agitation, said STPP being produced by:
a) producing granules of anhydrous essentially phase II STPP by heating of
sodium orthophosphate salts,
b) contacting the STPP granules with a quantity of water, the upper limit
being below the point at which the wetted granules commence to coalesce
and are no longer free flowing, the lower limit of water being that
quantity which is sufficient to maintain the free flowing granular
character of the STPP granules in aqueous media,
c) drying the wetted STPP granules from b) at a sufficient temperature to
expel unbound water but not the bound water, so that no more than 0.5% by
weight of unbound water remains, and
d) recovering the moisturized and dried, essentially phase II, granules
from c).
The term "essentially phase II" as used above and hereinafter refers to
phase II STPP, but which may contain very small amounts, not more than
about 5% by weight, of phase I STPP which is difficult to avoid
coproducing in manufacturing phase II STPP.
In a generally preferred method for realizing the herein moisturized phase
II granules, phase II STPP starting material is produced by heating sodium
orthophosphate salts, preferably "ortho liquor" in a rotary dryer at
temperatures favoring phase II STPP formation, and crushing and sizing the
rotary dryer product to give granules of anhydrous phase II STPP. Heating
temperatures employed are typically from about 465.degree. C. to about
475.degree. C.. Size distribution of the anhydrous granules ranges about
100% -14 mesh, 15% -100 mesh; preferably about 95% -20 mesh, 10% -100
mesh.
The granulated phase II STPP is then moisturized by contacting the
anhydrous granules of phase II STPP with water. A conventional
moisturizing technique consists in spraying water on a rolling bed of the
anhydrous granules contained in a rotary tube hydrator.
The quantity of water applied to the anhydrous phase II STPP granules can
vary considerably, the upper limit being below the point at which the
granules commence to coalesce and are no longer free flowing. Absorption
of as much as about 10% by weight of bound water is acceptable. Part of
the moisture taken up by the anhydrous granules is bound up in the hydrate
form and a portion is in the free or unbound form. In general, the total
water applied to the granules preferably runs about 5% to about 8% by
weight.
The lower limit of water in the moisturized granules is that quantity of
water, as determined by the still water caking test described hereinafter,
which is sufficient to maintain the free flowing granular character of the
granules when the granules are added to a volume of water in the absence
of agitation or stirring. This condition is met when the finished level of
bound water reaches about 3% by weight. Amounts of from about 5% to about
7% by weight bound water in the moisturized granules are preferred.
Removal of unbound water from the moisturized STPP granules is effected by
heating them at sufficient temperatures. In general, heating at
temperatures of about 60.degree. C. to 80.degree. C. serves to drive off
essentially all of the unbound water without an appreciable effect on the
bound water. Heating is conveniently effected in a rotating tube dryer in
which lift flights lift and pour the moistened granules through a
countercurrent flowing stream of hot air. The unbound water in the dried
granules is not above about 0.5% by weight, typically 0.3% to 0.5% by
weight water.
After recovery from the dryer, the granules are screened to give a size
distribution of about 100% -14 mesh, 3% -100 mesh.
The moisturized phase II STPP granules produced in accordance with the
invention remain in a granular state when added to non-agitated water, in
a still water caking test described below. There is no sign of caking
behavior, the granules forming a highly flowable, sandlike slurry.
The still water caking testing is performed by adding a sample of the
moisturized granular STPP or detergent composition containing same into
water in a ratio of 10 grams of STPP or detergent composition (as
appropriate) to 20 milliliters of quiescent water with only enough
movement of the sample with a stirring rod to wet the sample. After 5, 10
and 15 minutes probe the material to determine if it has set up into a
hard cake. If the material has not set up allow it to stand for up to one
hour, stir with a stirring rod and rapidly pour the mixture onto a flat
surface with an edge drain and observe if the solids are in discrete form
and readily flowable in the slurry.
The detergent formulation in which the present moisturized phase II
granules are preferably employed are those designed for automatic delivery
of a charge of the detergent, to a dishwasher or laundering machine from a
reservoir in a detergent dispenser, without requiring handling or contact
by personnel. These are typically high in alkalinity to facilitate better
cleaning performance. A typical detergent formulation has the following
ingredients:
a) sodium tripolyphosphate in amounts of about 10% to about 50% by weight,
b) alkalinity-imparting ingredients in amounts of about 10% to about 60% by
weight,
c) surface-active ingredients in amounts of about 0% to about 20% by
weight, and
d) oxidizing, soil and stain removing ingredients in amounts of about 0% to
about 12% by weight.
The above detergent formulation can be designed for use in either automatic
dishwashers or laundering machines employed in industrial and/or
institutional applications. The sodium tripolyphosphate employed in such a
formulation is the herein moisturized granules of essentially phase II
STPP containing from 3% to 10% by weight (preferably 5% to 7% by weight)
bound moisture and no more than 0.5% by weight (preferably 0.3% to 0.5% by
weight) of unbound moisture. The bound moisture and the use of essentially
phase II STPP are necessary to yield a STPP which remains as discrete
particulates, forming a flowable sandy slurry in the still water caking
test; and when used in detergent formulations the STPP yields a readily
flowable, non-caking detergent when it is placed in quiescent water. Also,
the low amount of unbound water in this product is helpful in not
degrading other components of the detergent formulation admixed with the
STPP which may be sensitive to moisture, particularly the oxidizing, soil
and stain removing ingredients such as chlorine-releasing agents, for
example, sodium dichloroisocyanuric acid, sodium perborates, sodium
carbonate peroxide (also called sodium percarbonate), optical brighteners
and enzymes.
The amount of the STPP employed in the formulation depends on the hardness
and temperature of the water employed, the degree of soiling of the
articles to be cleaned and the type of soils to be removed. Typical
formulations contain from about 10% to about 50% by weight STPP, with
heavy duty cleaning formulations employing the upper portion, that is,
about 25% to 50% by weight, of the range.
The second component, the alkalinity-imparting ingredients, is employed in
amounts of about 10% to about 60% by weight. The most common of these
ingredients employed are the alkali metal salts or alkali metal hydroxides
which are basic in aqueous solution. The most common and preferred are
sodium hydroxide, sodium carbonate and sodium silicates, including sodium
metasilicate and sodium orthosilicate. Also useful are alkali metal salts
such as potassium carbonate, potassium bicarbonate, potassium silicates,
sodium bicarbonate, sodium sesquicarbonate, potassium sesquicarbonate and
alkali metal hydroxides such as potassium hydroxide. These may be used
individually or in admixture with one another. For example, it is common
to use sodium silicate in addition to sodium carbonate or sodium hydroxide
because the sodium silicate, in addition to imparting alkalinity to the
formulation, also gives corrosion protection to equipment and enhances
cleaning as well.
The institutional dishwashing formulations tend to have higher alkalinity
than those employed in laundering and employ the more alkaline
ingredients, for example, sodium hydroxide and sodium silicate, and higher
amounts of such alkalinity-imparting ingredients, within the range set
forth above, than do formulations intended for laundering clothes. The
less alkaline laundering formulations employ less alkaline ingredients in
the lower portion of said range, alone, or in admixture with smaller
amounts of the more alkaline ingredients to achieve the required overall
alkalinity.
The third component, or surface-active ingredient, is employed both for its
surfactant cleaning properties as well as to control the degree of
foaming. The preferred ingredient is a nonionic surface-active agent which
is a non-soap synthetic detergent made up by condensation of alkylene
oxide groups (to form hydrophilic polyoxyalkylene groups) with an organic
hydrophobic compound. Among the hydrophobic compounds which can be used
are polyoxypropylene, the reaction product of propylene oxide and ethylene
diamine, aliphatic alcohols, alkylphenols, etc.
Examples of nonionic synthetic detergents useful in the present invention
are, condensation products of 6 to 30 moles, and preferably 7 to 11 moles,
of ethylene oxide with 1 mole of an alkylphenol containing 6 to 12 carbon
atoms in the alkyl group; condensation products of 6 to 30 moles of
ethylene oxide with 1 mole of an aliphatic straight or branch chained
alcohol containing 8 to 18 carbon atoms; condensation products of ethylene
oxide and the reaction product of propylene oxide and ethylene diamine;
nonyl phenol polyethoxy ethanol (commerically known as "Triton N" series);
isooctyl phenol polyethoxy ethanol (commercially known as "Triton X"
series). Another well known group of nonionic detergents is marketed as
"Pluronic" series. These compounds are the reaction products obtained by
condensing ethylene oxide with a hydrophobic base produced by the
condensation of propylene oxide with propylene glycol. The addition of
polyoxyethylene radicals to the hydrophobic based increases the water
solubility of the nonionic detergent and concurrently increases the
foaming properties of the detergent in aqueous solution in proportion to
the mole ratio of polyoxyethylene radicals to the hydrophobic base.
When making up dishwashing formulations, the preferred nonionic
surface-active ingredient is a surfactant such as Triton.RTM. CF-54,
Triton.RTM. DF-12, Pluronic.RTM. LF 61 or Pluronic.RTM. LF 62 because it
reduces foaming during the washing cycle. It is employed in small amounts
of 0% to about 2% by weight. Triton.RTM. CF-54 is an
octylphenoxypolyethoxyethyl butyl ether, while Triton.RTM. DF-12 is a
similar modified polyethyoxylated alcohol. Pluronic.RTM. LF 61 and
Pluronic.RTM. LF 62 are both block copolymers formed by condensing
ethylene oxide with a hydrophobic base formed by the condensation of
propylene oxide with propylene glycol, wherein the hydrophobic base has a
molecular weight of about 1500 to 1800. Often such surfactants can be
omitted from the dishwashing formulation because they are added directly
during the rinse cycle to improve rinsing action.
When the formulations are intended for washing machines to launder
clothing, the nonionic surface-active agent can be employed in amounts of
from 0 to 20 weight percent. When employed, the preferred nonionic
surface-active agents include alcohol alkoxylates, for example,
alkylphenol alkoxylates, and preferably alcohol ethoxylates or alcohol
propoxylates. However, the alcohol structure may vary considerably in
chain length. For example, surface-active agents such as Neodol.RTM.
91-2.5 is the reaction product of a C.sub.9 -C.sub.11 alcohol with an
average of 2.5 moles of a ethylene oxide to form a polyethoxylate. Other
similar nonionic surface-active agents which can be used in laundering
machine formulations include the following:
______________________________________
Surface-Active Agent
Structure
______________________________________
Neodol .RTM. 23-6.5
C.sub.12 -C.sub.13 alcohol ethoxylate
(1 mole C.sub.12 -C.sub.13 alcohol to
6.5 moles ethylene oxide)
Neodol .RTM. 91-6
C.sub.9 -C.sub.11 alcohol ethoxylate
(1 mole C.sub.9 -C.sub.11 alcohol to
6 moles ethylene oxide)
Triton .RTM. X-100
octylphenyl ethoxylate (1
mole of octylphenol to 10
moles of ethylene oxide)
Neodol .RTM. 25-7
C.sub.12 -C.sub.15 alcohol ethoxylate
(1 mole C.sub.12 -C.sub.15 alcohol
to 7 moles ethylene oxide)
Neodol .RTM. 25-9
C.sub.12 -C.sub.15 alcohol ethoxylate
(1 mole C.sub.12 -C.sub.15 alcohol to
9 moles ethylene oxide)
Neodol .RTM. 45-13
C.sub.14 -C.sub.15 alcohol ethoxylate
(1 mole of C.sub.14 -C.sub.15 alcohol to
13 moles ethylene oxide)
Neodol .RTM. 45-7
C.sub.14 -C.sub.15 alcohol ethoxylate
(1 mole of C.sub.14 -C.sub.15 alcohol to
7 moles of ethylene oxide)
______________________________________
In situations where foam control is not a problem, the surface-active
agents can be an anionic surface-active agent, alone or in combination
with other surface-active agents, either nonionic or anionic. The
preferred anionic surface-active agent employed in laundering machine
formulations is sodium dodecylbenzene sulfonate (Sulframin.RTM. 85).
Other water-soluble anionic sulfonate or sulfate surface-active agents
useful in the present composition include alkali metals salts of: alkyl
sulfonates, such as C.sub.10 -C.sub.20 alkyl sodium sulfonate; alkylaryl
sulfonates, such as C.sub.10 -C.sub.16 alkyl benzene sodium sulfonate;
alkene sulfonates, such as the C.sub.10 -C.sub.20 alkene sodium sulfonate;
alkyl sulfates, such as C.sub.8 -C.sub.20 alkyl sodium sulfates,
preferably sodium lauryl sulfate; alkylaryl sulfates, such as C.sub.10
-C.sub.16 alkyl benzene sodium sulfate; alkene sulfates, such as C.sub.10
-C.sub.20 alkene sodium sulfate. In laundering machine formulations, the
C.sub.10 -C.sub.14 alkyl benzene sodium sulfonates are the preferred class
of anionic surface-active agents useful in this invention.
If desired, additional surface-active agents may also be employed. They
include such additional surfaceactive agents as are compatible with said
nonionic surface-active agents, described previously, and anionic
sulfonate or sulfate agents, above described. An additional surface-active
agent is sodium ethoxylated alcohol sulfate, such as Neodol.RTM. 25-3S,
which is the reaction product of 1 mole of a C.sub.12 -C.sub.15 alcohol
with 3 moles of ethoxylate, and which is sulfated and recovered as its
sodium salt.
The fourth component, that is, the oxidizing, soil and stain removing
ingredients, is employed when additional cleaning ingredients are
necessary to achieve a higher degree of cleaning than is possible with the
other three ingredients, mentioned above. The ingredients include
chlorine-releasing agents, such as trichloroisocyanuric acid,
dichloroisocyanuric acid and alkali metal salts thereof, such as sodium
dichloroisocyanurate and hydrates thereof. Other compatible
chlorine-releasing agents, such as solid hypochlorites, for example,
calcium hypochlorite, may also be employed.
Other such ingredients, typically used in laundry formulations, include the
hydrogen peroxide-derived compounds such as alkali metal perborates, for
example, sodium perborate and hydrates thereof, alkali metal carbonate
peroxide (also called alkali metal percarbonates), for example, sodium
carbonate peroxide, which may be used alone or with activators such as
tetraacetyl diamine (TAED); and enzymes for better detergency. Optical
brighteners are often added to laundry formulations to add a desirable
whiteness to the article being laundered.
When required in the formulation to enhance cleaning any of these
oxidizing, soil and stain removing ingredients, or mixtures thereof, are
employed in total amounts of 0% to about 12% by weight in the formulation.
In addition to the above ingredients, the formulation may also contain
other well-known ingredients normally used such as coloring agents,
perfumes, foam depressants, corrosion control additives and other such
conventional ingredients.
Reference is now made to the following non-limiting examples.
EXAMPLE 1
Following the above described procedure, a specimen of granular,
essentially phase II STPP was produced by calcining ortho liquor in a
rotary dryer at 465.degree. C. to 475.degree. C., and screened to yield a
product having a mesh size of 100% -14 mesh. The granules were treated
with water to give a total water content of about 7% to 8% by weight of
the total composition. The treated granules were dried at between
60.degree. C. and 80.degree. C. to remove free water. The resulting
moisturized granular phase II STPP had a bound water concentration of 6%.
It was screened to yield a sized material of 100% -14 mesh, 3% -100 mesh.
Its unbound water content was 0.5% by weight.
The product formed a free flowing, sandy slurry of STPP granules in the
still water caking test.
EXAMPLE 2
In this Example carried out as in Example 1, the moisturized phase II STPP
granular starting material contained 7% by weight water and the back dried
product contained 6% by weight bound water. The residual unbound water was
a 0.5% by weight. The STPP granules formed discrete particles of a sandy
slurry when subjected to the still water caking test.
EXAMPLES 3-7
These Examples using the above described procedure were carried out to
determine the minimal quantity of moisture content in the finally
processed phase II STPP granules to prevent caking and maintain the
granularity of the granules in non-agitated water. The Examples correspond
to final moisture concentration by weight of 0%, 1%, 3%, 5% and 7%,
respectively. When the samples were submitted to the still water caking
test, it was observed that, at 0% treatment, the phase II formed a hard,
rocky lump; at 1%, a cake was formed but it was not as hard as that
produced at 0% water. At the 3% level, caking tendency was decreasing and
the STPP was beginning to exhibit the property of retaining its
granularity. At the 5% and 7% levels, the STPP formed a readily flowable
slurry of individual granules.
EXAMPLE 8
A detergent formulation high in alkalinity was formulated, typical of those
employed in institutional dish washing detergents, having the following
components, by weight:
______________________________________
a) sodium tripolyphosphate
35%
(produced as set forth in
Example 1 and containing
essentially phase II with 6%
by weight bound water and
0.5% by weight unbound water)
b) sodium hydroxide 58%
c) sodium carbonate 4.8%
d) nonionic surface-active agent
0.6%
(Triton .RTM. CF-54)
e) sodium silicate 1.5%
______________________________________
The formulation was subjected to the still water caking test and found not
to cake after 5 minutes of standing in quiescent water and at 5 minute
intervals thereafter as required in the test procedure. After standing in
quiescent water for not quite one hour, the mixture on being stirred and
poured on a flat surface was found to be free flowing with slight
granulation of ingredients.
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